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MPEG captures w/AIW 9800 smaller than AIW 7500?

Discussion in 'ATI' started by Fountainhead, Nov 10, 2003.

  1. Fountainhead

    Fountainhead Guest

    I previously used an AIW 7500 to capture shows via the TV tuner and burn
    to DVD. I had 3 custom MPEG-2 capture settings for 1 Hr, 2 Hr, 3 Hr,
    depending on how much I needed to fit on a single DVD. The settings were
    all basically the same (352 x 480) with the bitrate set differently for
    each. I just built a new PC around the AIW 9800. I re-created the exact
    custom settings on the 9800, but I notice that the resulting MPEG files
    are smaller than they were on the 7500. For example, 1 Hr of MPEG
    recorded on my 1 Hr setting produces an MPEG of ~2900MB, compared to
    approx 4000MB on the 7500.

    Not that this is a bad thing, but it makes me wonder if I'm overlooking
    something. Or is the MPEG encoding on the 9800 more efficient somehow?
     
    Fountainhead, Nov 10, 2003
    #1
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  2. Fountainhead

    LastYJ Guest

    It's possible that you have enabled "Video Soap" with the newer version of
    MMC you are now using with the AIW 9800. Video Soap allows you to clean up
    the picture you are capturing. It's helpful especially when you don't have
    a crystal-clear source. So, with less noise in your picture, the resulting
    MPEG file will be smaller in size.

    -lyj
     
    LastYJ, Nov 10, 2003
    #2
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  3. Fountainhead skriblede:
    Are you using the same version of the capture software (MMC)?

    The encoding takes place in software - not hardware.

    David
     
    David T. Metz, Nov 10, 2003
    #3
  4. Fountainhead

    Fountainhead Guest

    I was using 8.5 with the 7500, and 8.7 with the 9800. In response to the
    other poster, I am using the same Video Soap settings as before. One
    thing thing that *is* different is that the 9800 has "hardware assisted*
    MPEG encoding, and the 7500 does not. I don't know if that has anythig
    to do with it or not.
     
    Fountainhead, Nov 10, 2003
    #4
  5. Fountainhead skriblede:
     
    David T. Metz, Nov 11, 2003
    #5
  6. Fountainhead

    Fountainhead Guest

    Video Soap showed up in MMC 8.1. I was using 8.5 with the 7500. You
    *can* use video soap with the 7500 with MMC 8.x. I was able to get the
    later MMC's as I have a 9700 Pro in another PC, so I had the proper
    original CD's for verification, etc. And ATI says that the AIW 9800 has
    "hardware assisted encoding", which I take to mean that real-time MPEG
    encoding is at least partially processed via the card itself. The 7500
    definitely has no hardware assist.
     
    Fountainhead, Nov 11, 2003
    #6
  7. Fountainhead skriblede:
    Ah. Well I read up a bit and it seems that videosoap uses the graphics
    chip's pixel shader to calculate its filtering as well as using the cpu.
    Perhaps this explains it. The video soap can use the R350's pixel shader
    but I believe the 7500 (dunno chip name) has no pixel shader capabilities
    and is thus not able to utilize video soap to its fullest?

    I read anout VS here:
    http://www.anandtech.com/video/showdoc.html?i=1740&p=3
    True - I remembered wrongly from another discussion where someone claimed
    the card did hardware encoding. It does assist in encoding.
    Agreed.

    David
     
    David T. Metz, Nov 11, 2003
    #7
  8. Fountainhead

    Fountainhead Guest

    Interesting link, thanks. I'll post my findings here (AIW 9800 vs AIW
    7500) in case anyone pulls this up via google at some later date. I
    created a DVD containing clips made with each of my custom settings (1,
    2 and 3 hr) and I can say that the quality of each of these is noticably
    better than what I got from the AIW 7500 with the same settings. The 3
    Hr setting in particular was FAR better than before.

    For the record, here are my settings using MMC 8.7:

    MPEG-2 at 352x480
    Encode Interlaced
    48,000 KHz Stereo
    P Frames 4
    B Frames 2
    Do not check 3:2 pulldown
    Check the little box for Closed Group of Pictures
    1 Hr - 8.5 MBit
    2 Hr - 4.42 MBit
    3 Hr - 2.93 MBit
    (These are set up to record approx 3.9 GB in the alloted time)
    Motion Estimation 100%
    Audio Encoding 224Kbit
    Video Soap - Comb Filter #1 - 70%

    These all record with no dropped frames. One thing that I find
    interesting is that TV captures made at 352x480 actually look better
    than those recorded at 720x480, with all other settings the same. I
    would have thought the 720x480 would produce a better video image, but
    it doesn't. I wonder why?
     
    Fountainhead, Nov 11, 2003
    #8
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